Magnesium Aluminate (MgAl2O4 or Spinel) crystals and Substrates

Magnesium Aluminate  (MgAl2Oor spinel) single crystals are widely used for bulk acoustic wave and microwave devices and fast IC epitaxial substrates. It is also found that MgAl2O4 is a good substrate for III-V nitrides device. Spinel (MgAl2O4) is one candidate for such GaN LDs substrate. The crystallographic structure of MgAl2O4 is a spinel type (Fd3m), and its lattice constant is 8.083 A. MgAl2O4 is a relatively low-cost substrate material, which has been successfully applied to the growth of high quality GaN films. MgAl2O4 is cleaved on the (100) plane. GaN LD cavities have been obtained by simply cleaving MgAl2O4 substrates along the (100) direction, which will also work well for ZnO. MgAl2O4 crystal is very difficult to grow, due to the difficulty in maintaining a single phase structure.